As a fellow member with no authority over them, stepping in yourself only adds to the commotion. A report is the best option there.
If you see a thread in the wrong section, reporting is all you can do since you can't move it yourself. You can still respond as normal though...and don't think you'll be punished for mentioning it's in the wrong section.
The goal isn't to punish as many people as possible, after all. Every rule is subject to common sense, so we won't be throwing out unreasonable infractions due to technicalities.